1. Field of the Invention
The present invention relates to a motor, and more particularly, to a motor capable of disc labeling by including a low-speed control magnet, generating a pulse for low-speed control (hereinafter “low-speed control pulse”), on the outer circumferential surface of a magnetic coupling portion of a rotor case.
2. Description of the Related Art
In general, a spindle motor installed inside an optical disc drive rotates a disc so that an optical pickup mechanism can read data written to the disc.
Recently, an optical disc drive equipped with a LightScribe function has been increasingly released onto the market. Here, the LightScribe function allows users to print letters (characters) or images freely on the upper side of a disc such as a DVD, a CD or the like.
According to the related art, LightScribe discs that support the LightScribe function by having a printed encoder generating an FG pulse for low-speed control, are required in order to implement the LightScribe function. Here, typical discs for recording cannot be used in realizing the LightScribe function.
That is, in order to use the LightScribe function, a spindle motor needs to rotate at a low speed of 40 rpm to 300 rpm or less. Thus, an encoder generating a separate FG pulse is formed on the side of a disc, since the FG pulse of the spindle motor itself, which rotates at a speed of 12,000 rpm, cannot be used for the LightScribe function.
Further, an optical encoder sensor, including a light receiving part and a light emitting part, is required in order to detect signals from the encoder formed on the side of the disc. As mentioned above, the optical encoder sensor includes the light emitting part and the light receiving part. The light emitting part emits beams onto the reflective and non-reflective surfaces of the encoder formed on the disc which is in rotation. The light receiving part receives successive signals on the basis of beams reflected from the reflective and non-reflective surfaces. A controller then controls the rotational speed of the spindle motor on the basis of those successive signals received by the light receiving part.
However, the use of such LightScribe discs has limitations in that the discs are costly and are not easy to buy.
In addition, since LightScribe printing is performed on the opposite side to the read/write-side of a disc, the LightScribe disc is repetitively taken out from and put back into a chucking device. This may damage an encoder printed on the LightScribe disc.
Further, the encoder, when printed on a disc in a non-uniform manner, fails to perform precise low-speed control and impairs printing quality.
In addition, the optical encoder sensor is manufactured using a semiconductor manufacturing process, thereby increasing manufacturing costs.